Ozone is a very powerful oxidant, and has many commercial applications. One application of ozone is in the purification of drinking water. Ozone may be used to purify drinking water either on a small scale or on a large scale. For example, existing municipal water treatment facilities have been upgraded to use ozone to purify drinking water. One of the benefits of using ozone as a water purifier is that at standard water treatment conditions it decomposes into molecular oxygen very quickly, leaving little residual contaminants.
Ozone is typically produced by the reaction between molecular oxygen and monoatomic oxygen. The equilibrium of the chemical reaction may be represented by equation I: EQU O.sub.2 +O&lt;= = = = = = = = =&gt;O.sub.3 (I)
One significant problem encountered in the commercial production of ozone is that the required monoatomic oxygen exists only at temperatures above about 2300.degree. K. However, ozone is stable only at lower temperatures, eg. below about 1000.degree. K. At temperatures above about 1000.degree. K, ozone dissociates to form molecular oxygen and monoatomic oxygen. At temperatures below 2300.degree. K, monoatomic oxygen recombines to form molecular oxygen. This is problematic since temperatures above 2300.degree. K are necessary to form the monoatomic oxygen required to produce ozone, yet the ozone itself is almost immediately destroyed at temperatures above 1000.degree. K.
In an effort to overcome this significant problem, attempts have been made to commercially produce ozone at low temperatures (below about 500.degree. K) in order to increase its useful life. While attempts to date have been moderately successful, they have significant drawbacks, in that the total volume of ozone capable of being produced is small.
A typical method for the commercial production of ozone uses high voltage corona discharges. These discharges produce energized electrons which are supplied to a source of molecular oxygen, causing the molecular oxygen to dissociate into monoatomic oxygen. Some of the monoatomic oxygen then reacts with molecular oxygen, via a three-body interaction, to form ozone. Because the gas source of molecular oxygen is maintained at a low temperature (below 500.degree. K), a significant portion of the ozone produced survives to its point of use. However, overall this method is inefficient because only a small amount of molecular oxygen is converted into monoatomic oxygen by the excited electrons. That is, a very large number of electrons (and a correspondingly large amount of energy to produce the electrons) is required to produce a very small amount of monoatomic oxygen. This is the rate limiting step in the production of ozone by this method. These types of systems are only capable of producing a small net amount of ozone.
Alternately, ozone may be produced with ultraviolet radiation. In this method, ultraviolet light photons are bombarded at molecular oxygen, causing molecular oxygen to dissociate into monoatomic oxygen. The monoatomic oxygen then reacts with molecular oxygen via the three bodied interaction to form ozone. This reaction proceeds by the Chapman mechanism, which is essentially how ozone is created in the upper atmosphere of the earth. As with the high voltage method of creating ozone, ozone production with ultraviolet light is limited since the vast majority of ultraviolet radiation passes through oxygen without causing the molecular oxygen to dissociate. That is, the limiting step in the formation of ozone is the formation of monoatomic oxygen.
In each of these systems, it is only possible to obtain a significant production of ozone by operating a large number of systems in parallel. This results in large acquisition and operating costs. Therefore, there remains a need to develop a method of producing significant quantities of ozone on a cost effective, commercial scale basis, and which has a useful life before deterioration.